Projectile



1M. 9, w43. R1 HURLEY 2,310,915

PROJECTILE Filed April 16, 1938 Watentec'l Feb.. lid

Roy 'l. Hurley, Dobbs llerry, N. Y., assigner to Bendix Aviation Corporation, South Bend, ind., a corporation ol. Delaware Application April 16, 1938, Serial No. 202,399

Claims. (Cl. 102-93) This invention relates to projectiles and more particularly to projectiles of the type having a rotating band and to methods and means for iixing the rotating band thereto.

ln the methods heretofore proposed for securing a rotating band to a projectile, an oversized ring of soft metal is generally pressed into a dovetail groove in the projectile blank by applying compressive pressure to reduce the diameter of said ring and conform the same to the shape of the groove. The high pressure which is necessarily applied to conform the soit metal band to the shape of the groove distorts the metal and sets up internal stresses within the iinlshed rotating band which tend to weaken the same. Often, as a result of this weakness or because of inadequate compression of the metal ring to completely ll the groove, the joint between the projectile blank and the rotating band is not gas-tight. Accordingly, gas leakage frequently occurs between the band and the projectile when the same are ired from a gun, thereby decreasing the eiiiciency of the explosive charge and causing the projectile to fall short of its intended target. Furthermore, the leakage of the high pressure gases of explosion between the rotating band and the projectile tend to loosen the :former to such an extent that the same will be thrown from the projectile by centrifugal forces acting thereon as the rapidly rotating shell leaves the gun. The loss of the rotating band aects the trajectory of the projectile and, in addition, imperils the personnel in the vicinity of the gun. Because of the necessity for distorting the metal of the rotating band in the methods heretofore employed, the hardness and types of metals which may be employed in practicing said methods is unduly restricted.

Accordingly, one of the objects of the present invention is to provide a novel projectile of the type having a rotating band, said projectile being so constructed that the foregoing disadvantages are obviated.

Another object of the invention is to provide a novel method for applying a rotating band to a projectile whereby said band is caused to become, in edect, an integral part of the projectile.

A further object is to provide a novel method oi applying a rotating band to a projectile which method permits of the use of metals having a wider range or properties such as hardness, ductility, melting point, etc.

Still another object is to provide novel means tor carrying out the novel method comprehended by the invention, said `means .being so constituted as to compensate for the thermal expansion of the projectile during the application of the rotating band thereto.

The above and further objects and novel fea tures of the invention will more fully appear from the following detailed description when the same is taken in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for the purpose of illustration only and is not designed as a denition of the limits of the invention, reference being had primarily for this latter purpose to the appended claims.

In the drawing, wherein like reference characters refer to like parts throughout the several views,

Fig. l is a longitudinal sectional view `taken substantially along line t-l of Fig. 2, showing one form of the novel appparatus comprehended by the present invention, said apparatus being shown inoperative position on a projectile;

lig, 2 is a transverse sectional view taken substantially along line 2-2 of Fig. 1; and,

Fig. 3 is a plan view of a completed projectile.

In the illustrated embodiment, one form of means suitable for carrying out the novel process of the invention is shown as comprising a mold il which completely encircles a portion of the projectile blank 5 and engages the periphery of the latter on opposite sides of an annular groove t provided in said blank for positioning a rotating band 'i (Fig. 3). Mold i is provided with a groove t which is adapted to register and cooperate with groove 6 to form an annular channel of the` same size and shape as the desired rotating band l. Mold l is preferably split along the' extension of a horizontal diameter of projectile 5, into two separable sections "la and Ab, the former, as shown, being the upper section and having a funnel or cup-shaped opening A therein, which communicates with the channel formed by grooves ii and 8.

Means are provided for tightly clamping mold sections da, and tb to each other around projectile 5 and in the illustrated embodiment said means comprise a pair of arms I0 and il (Fig. 2) pivotally secured to opposite sides of section tb by means of pins i2 and i3, respectively. Said arms are adapted to pivot in the direction of section Ala and to have the free ends thereof extend over slightly concaved shoulders lil formed on opposed sides of said section. Cam levers it and I6 are pivotally secured to the free ends of arms il) and il, respectively, for rotation relative to the latter. When said levers are pivoted upwardly and inwardly to the positions shown in Fig. 2, the cam-shaped portions of said levers bear against shoulders Inl and apply a pressure thereto in the direction of section lib. Sections da and lib may be thus tightly clamped to each other and to projectile blank 5.

In practicing the novel method comprehended by the present invention for applying rotating band 'l to projectile blank 5, the latter is rst positioned in mold il so that the edges of groove 5 coincide with or are suitably positioned relative to the edges of groove 0. Arms I and H are pivoted in the direction of section a until the cam surfaces of levers I5 and I6 are directly over shoulder Id and then said levers are pivoted upwardly and inwardly to cause a pressure to be applied to shoulders It, thereby clamping section la to section lib. A metallic slug Il from which rotating band 'l is to be formed is then inserted into opening or conduit 0 and the whole is placed in a furnace having a reducing atmosphere, such as in a hydrogen furnace. 'I'he temperature within the furnace is then raised until slug Il melts and the molten metal ows into the channel formed by grooves t and il. The metal, preferably a copper alloy, from which slug Il is made, is so chosen that when the same is in a molten state, it will wet the surfaces of groove 6. Thus, when the mold and projectile blank are permitted to cool, the rotating 'band is cast in place and fused to the steel projectile so as to form an integral part thereof. It will be understood that groove 5 may be dovetailed, if desired, but this is not necessary to secure an adequate bond between the band and projectile when practicing the method of the present invention.

Slug Il which is preferably composed of copper or a copper alloy determines the composition of mold il since the latter must be formed from, or at least coated with, a metal, such as stainless steel, which will not be wet by the metal constituting the slug when the latter is in a molten state. In other words, mold t must be formed from a metal which will not fuse with the copper or other suitable metal of slug Il in the reducing atmosphere of the furnace. Accordingly, when the liquefied metal flows into channel 6 5, it will become fused or brazed only to the surface of groove 6, thereby rigidly fixing the subsequently solidified band 1 to projectile 5 and permitting the ready removal of mold sections da and lb after solidifcation.

In order to insure against any possible leakage of the molten metal between the engaging surfaces of mold l and shell body 5, the former is made of metal which preferably has a coeflicient of thermal expansion equal to or slightly less than the coefficient of thermal expansion of body 5. It has been determined that, if the projectile is made of a mild steel having a coeiilcent'of thermal expansion of about .0000063 inch per degree Fahrenheit, for example, the mold may be made of a stainless steel commercially known as Carpenter No. 2 which has a chromium content of from 12 to 14 per cent and a carbon content of' .3 per cent and which has a coefficient of thermal expansion of about .0000056 inch per degree Fahrenheit. A suitable metal which may be employed in spiders making the mold is commercially known as Firth Sterling AA and is a stainless steel having a chromium content of from 13 to 14 per cent and a very low carbon content and having a coefficient of thermal expansion of about .0000059 inch per degree Fahrenheit. To further insure against leakage of the molten metal, the surfaces of mold il which are in contact with the periphery of projectile 5, and the surfaces of sections la and lib which engage each other when said sections are clamped in operative position may be coated or plated with a silicate of soda or a graphite paint. The inclusion of a film of said plating or paint between the contacting surfaces effectively prevents any leakage of the molten metal between said surfaces.

There is thus provided a novel method for producing a novel projectile having a rotating band which is fused to the projectile body. The fusion of band to body produces a rrn bond therebetween and eliminates the possibility of leakage of gases of explosion between the band and the projectile body and the danger of said band being thrown from the shell by centrifugal forces. The eciency andl accuracy of the firing is thereby increased and the dangers to the personnel are materially reduced.

Although only a single embodiment of this invention has been illustrated and described, it is to be expressly understood that the same is not limited thereto, but that various changes may be made therein. For example, metals having properties different from those of copper or a copper alloy may be employed, if desired, for the rotating band and a metal other than stainless steel may be utilized in making the mold. Changes in the design and arrangement of parts may also be made Without departing from the spirit and scope of the invention, as will now be understood by those skilled in the art. For a definition of the limits of the invention, reference will be had primarily to the appended claims.

What is claimed is:

l. A projectilel comprising a body of hard metal and a rotating band formed from an alloy having copper as a principal ingredient thereof, said band being fused directly to said body to form a bond with the metal of said body.

2. A projectile comprising a body of steel and a band of copper alloy, said band being fused to said body.

3. A projectile comprising a metallic body, and a metallic rotating band of copper fused directly to said body.

4. A projectile comprising a metallic body portion having a peripheral groove, and a metallic rotating band formed from an alloy having copper as a principal ingredient thereof, said band being anchored in said groove and fused directly to the surface thereof.

5. A projectile comprising a body made of hard metal, such as steel, said body having a peripheral groove therein, and a Vband of copper alloy anchored in said groove and fused to said body, said band having a greater outside diameter than Said body.

ROY T. HURLEY. 

